Light-emitting device

ABSTRACT

A light-emitting device including: a light-emitting stacked layer having first conductivity type semiconductor layer, a light-emitting layer formed on the first conductivity type semiconductor layer, and a second conductivity type semiconductor layer formed on the light-emitting layer, wherein the upper surface of the second conductivity type semiconductor layer is a textured surface; a first planarization layer formed on a first partial of the upper surface of the second conductivity type semiconductor layer; a first transparent conductive oxide layer formed on the first planarization layer and a second partial of the second conductivity type semiconductor layer, including a first portion in contact with the first planarization layer and a second portion having a first plurality of cavities in contact with the second conductivity type semiconductor layer; and a first electrode formed on the first portion of the first transparent conductive oxide layer.

BACKGROUND

1. Technical Field

This application relates to a light-emitting diode device, and moreparticularly to a high light extraction light-emitting diode device.

2. Reference to Related Application

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/581,439, entitled “LIGHT-EMITTING APPARATUS”, filed on Oct.17, 2006, now abandoned the entire contents of which are incorporatedherein by reference.

3. Description of the Related Art

Light-emitting diode (LED) devices are widely used in different fieldssuch as displays, traffic lights, data storage apparatus, communicationapparatus, lighting apparatus, and medical apparatus. One important taskfor engineers is to increase the brightness of the LED devices.

In a known LED device, the semiconductor layer of the LED device havinga textured surface can have higher light extraction efficiency. However,the textured surface can lower lateral current conduction and currentspreading so the forward voltage is higher.

SUMMARY

A light-emitting device including: a light-emitting stacked layer havingfirst conductivity type semiconductor layer, a light-emitting layerformed on the first conductivity type semiconductor layer, and a secondconductivity type semiconductor layer formed on the light-emittinglayer, wherein the upper surface of the second conductivity typesemiconductor layer is a textured surface; a first planarization layerformed on a first part of the upper surface of the second conductivitytype semiconductor layer; a first transparent conductive oxide layerformed on the first planarization layer and a second part of the secondconductivity type semiconductor layer, including a first portion incontact with the first planarization layer and a second portion having afirst plurality of cavities in contact with the second conductivity typesemiconductor layer; and a first electrode formed on the first portionof the first transparent conductive oxide layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide easy understanding ofthe application, and are incorporated herein and constitute a part ofthis specification. The drawings illustrate embodiments of theapplication and, together with the description, serve to illustrate theprinciples of the application.

FIGS. 1A-FIG. 1F illustrate a process flow of a method of fabricating alight emitting device in accordance with a first embodiment of thepresent application.

FIG. 1G is a top view of a second semiconductor layer in accordance witha first embodiment of the present application.

FIG. 1H is an SEM diagram showing a surface morphology of an ITO layerin accordance with a first embodiment of the present application.

FIGS. 2A-2D are cross-sectional views of a light-emitting device inaccordance with a horizontal type embodiment of the present application.

FIG. 3 is a cross-sectional view of a light-emitting device inaccordance with a third embodiment of the present application.

FIG. 4 is a cross-sectional view of a light-emitting device inaccordance with a fourth embodiment of the present application.

FIG. 5 is a cross-sectional view of a light-emitting device inaccordance with a fifth embodiment of the present application.

FIGS. 6A-6B are top views of a second semiconductor layer in accordancewith a first embodiment of the present application.

FIGS. 7A-7B are top views second semiconductor layer in accordance witha second embodiment of the present application.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference is made in detail to the preferred embodiments of the presentapplication, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are used in thedrawings and the description to refer to the same or like parts.

The present disclosure describes a light emitting device and a method offabricating the light emitting device. In order to have a thoroughunderstanding of the present disclosure, please refer to the followingdescription and the illustrations of FIG. 1A to FIG. 7.

FIGS. 1A to 1F illustrate a process flow of the method of fabricating alight emitting device in accordance with a first embodiment of thepresent application. Referring to FIG. 1A, a light-emitting devicecomprises a conductive substrate 10; a light emitting stack 12 includinga first conductivity type semiconductor layer 124, a light-emittinglayer 122 and a second conductivity type semiconductor layer 120sequentially formed on the first surface 101 of the conductive substrate10 wherein the upper surface 1201 of the second conductivity typesemiconductor layer 120 has a textured surface formed by an epitaxymethod, an etching method, or the combination thereof. The material ofthe light emitting stack 12 contains one or more elements selected fromthe group consisting of Ga, Al, In, As, P, N and Si, such as aluminumgallium indium phosphide (AlGalnP) series material, aluminum galliumindium nitride (AlGaInN) series material and so on. The light-emittinglayer 122 can be a single heterostructure (SH), a double heterostructure(DH), a double-side double heterostructure (DDH), or a multi-quantumwell (MWQ). Besides, the wavelength of the emitting light can also beadjusted by changing the number of the pairs of the quantum well.

Referring to FIG. 1B, a first planarization layer 13 is formed to coverand fill the textured spaces of the upper surface 1201 of the secondconductivity type semiconductor layer 120. The first planarization layer13 can be formed by spin coating method such as spin-on glass (SOG) orbenzocyclobutene (BCB). In one embodiment of this application, the SOGcan be a dielectric material mixture of SiO₂ and dopants (either boronor phosphorous) that is suspended in a solvent solution. The SOG canalso be polymers such as HSQ (Hydrogen silesquioxane) or MSQ(Methylsequioxane).

Referring to FIG. 1C, the first planarization layer 13 is patterned andsolidified to form a second planarization layer 131 by etching orlithography method wherein part of the upper surface 1201 of the secondconductivity type semiconductor layer 120 is exposed and not covered bythe second planarization layer 131. The position of the secondplanarization layer 131 is not specified and can be formed in the middleor the edge of the second conductivity type semiconductor layer 120.

Referring to FIG. 1D, a first transparent conductive oxide layer 14 isformed to cover the entire second planarization layer 131 and part ofthe upper surface second conductivity type semiconductor layer 1201. Thefirst transparent conductive oxide layer 14 includes a first portion 141and a second portion 142, wherein the first portion 141 is formed incontact with the entire second planarization layer 131 which issubstantially flat, and the second portion 142 is formed on the uppersurface of the second conductivity type semiconductor layer 1201 havinga first plurality of cavities 1421 in contact with the upper surface ofthe second conductivity type semiconductor layer 1201 and a secondplurality of cavities 1422 formed in the upper surface of the secondportion 142 which is opposite to the first plurality of cavities 1421.The first plurality of cavities 1421 are shaped into cones or pyramids(as shown in FIGS. 1G-1H) and formed by an epitaxy method, an etchingmethod, or the combination thereof. The second plurality of cavities1422 are shaped into a cone or a pyramid by an etching process andextended downwards to the first plurality of cavities 1421 of the firsttransparent conductive layer 14, wherein the direction of the extensionis preferably perpendicular to the top surface of the conductivesubstrate 10.

Referring to FIG. 1E, a first electrode 15 is formed on the firstportion 141 of the first transparent conductive oxide layer 14; and asecond electrode 16 is formed on the second surface 102 of theconductive substrate 10. The material of the electrode structurementioned above can be metal material such as Cr, Ti, Ni, Pt, Cu, Au,Al, or Ag.

Referring to FIG. 1F, in another embodiment of this application, a firstreflective metal layer 17 can be formed on the first portion 141 of thefirst transparent conductive oxide layer 14; a first electrode 15 can beformed on the first reflective metal layer 17 to improve thelight-emitting efficiency.

In accordance with the first embodiment of the present application, byforming the second planarization layer 131 the part of the transparentconductive oxide layer 14, the first electrode 15 and the firstreflective metal layer 17 can be formed on a substantially flat surface,and the impedance and the forward voltage can be decreased and thelateral current conduction, current spreading and efficiency can beincreased.

Besides, the first plurality of cavities 1421 are extended downwardsfrom the surface of the second semiconductor layer 120 and make theupper surface of the second portion 142 of the first transparentconductive oxide layer 14 conformally formed on the second semiconductorlayer 120 and have the second plurality of cavities 1422. The adhesionstrength between the first reflective metal layer 17 and the firsttransparent conductive oxide layer 14 has been improved by the firstplurality of cavities 1421. The result of a peeling test for the devicemade in accordance with the first embodiment and the conventional LEDdevice without cavities on the surface of the first transparent oxidelayer shows that all the devices in accordance with the first embodimentpassed the peeling test, but more than 80% of the conventional LEDdevices failed in the peeling test. By the combination of the flat andtextured first transparent oxide layer, the lower efficiency and peelingissues are solved.

FIGS. 2A-2D are cross-sectional views of a light-emitting device inaccordance with a horizontal type embodiment of the present application.Referring to FIG. 2A, a light-emitting device comprises a substrate 20;a light emitting stack 22 including a first conductivity typesemiconductor layer 224, a light-emitting layer 222 and a secondconductivity type semiconductor layer 220 sequentially formed on thefirst surface 201 of the substrate 20 wherein the upper surface 2201 ofthe second conductivity type semiconductor layer 220 has a texturedsurface formed by an epitaxy method, an etching method, or thecombination thereof. The light emitting stack 22 is etched, and part ofthe first semiconductor layer 224 is exposed to form a horizontal typelight emitting device.

The material of the light emitting stack 22 contains one or moreelements selected from the group consisting of Ga, Al, In, As, P, N andSi, such as aluminum gallium indium phosphide (AlGaInP) series material,aluminum gallium indium nitride (AlGaInN) series material and so on. Thelight-emitting layer 222 can be a single heterostructure (SH), a doubleheterostructure (DH), a double-side double heterostructure (DDH), or amulti-quantum well (MWQ). Besides, the wavelength of the emitting lightcan also be adjusted by changing the number of the pairs of the quantumwell.

Following a similar process as the first embodiment, a firstplanarization layer (not shown) is formed by spin coating method such asspin-on glass (SOG) or benzocyclobutene (BCB) to cover and fill thetextured spaces of the upper surface 2201 of the second conductivitytype semiconductor layer 220. The first planarization layer 23 can beformed by spin coating method such as spin-on glass (SOG) orbenzocyclobutene (BCB). In one embodiment of this application, the SOGcan be a dielectric material mixture of SiO₂ and dopants (either boronor phosphorous) that is suspended in a solvent solution. The SOG canalso be polymers such as HSQ (Hydrogen silesquioxane) or MSQ(Methylsequioxane).

Then, the first planarization layer (not shown) is patterned andsolidified to form a second planarization layer 231 by etching orlithography method wherein part of the upper surface 2201 of the secondconductivity type semiconductor layer 220 is exposed and not covered bythe second planarization layer 231. The position of the secondplanarization layer 231 is not specified and can be formed in the middleor the edge of the second conductivity type semiconductor layer 220.

Following, a first transparent conductive oxide layer 24 is formed tocover the entire second planarization layer 231 and part of the uppersurface second conductivity type semiconductor layer 2201. The firsttransparent conductive oxide layer 24 includes a first portion 241 and asecond portion 242, wherein the first portion 241 is formed in contactwith the entire second planarization layer 231 which is substantiallyflat, and the second portion 242 is formed on the upper surface of thesecond conductivity type semiconductor layer 2201 having a firstplurality of cavities 2421 in contact with the upper surface of thesecond conductivity type semiconductor layer 2201 and a second pluralityof cavities 2422 formed in the upper surface of the second portion 242which is opposite to the first plurality of cavities 2421. The firstplurality of cavities 2421 are shaped into cones or pyramids and formedby an epitaxy method, an etching method, or the combination thereof. Thesecond plurality of cavities 2422 are shaped into a cone or a pyramid byan etching process and extended downwards to the first plurality ofcavities 2421 of the first transparent conductive layer 24, wherein thedirection of the extension is preferably perpendicular to the topsurface of the substrate 20.

Finally, a first electrode 25 is formed on the first portion 241 of thefirst transparent conductive oxide layer 24; and a second electrode 26is formed on the exposed first semiconductor layer 224. The material ofthe electrode structure mentioned above can be metal material such asCr, Ti, Ni, Pt, Cu, Au, Al, Ag, or the alloy thereof. By the combinationof the flat and textured first transparent oxide layer, the lowerefficiency issues are solved.

Referring to FIG. 2B, In another embodiment of this application, a firstreflective metal layer 27 can be formed on the first portion 241 of thefirst transparent conductive oxide layer 24; a first electrode 25 can beformed on the first reflective metal layer 27 to improve thelight-emitting efficiency.

The first plurality of cavities 2421 are extended downwards from thesurface of the second semiconductor layer 220 and make the upper surfaceof the second portion 242 of the first transparent conductive oxidelayer 24 conformally formed on the second semiconductor layer 220 andhave the second plurality of cavities 2422. The adhesion strengthbetween the first reflective metal layer 27 and the first transparentconductive oxide layer 24 has been improved by the first plurality ofcavities 2421. The result of a peeling test for the device made inaccordance with the first embodiment and the conventional LED devicewithout cavities on the surface of the first transparent oxide layershows that all the devices in accordance with the first embodimentpassed the peeling test, but more than 80% of the conventional LEDdevices failed in the peeling test. By the combination of the flat andtextured first transparent oxide layer, the lower efficiency and peelingissues are solved.

Referring to FIG. 2C, in another embodiment of this application, thedifference between the FIG. 2A and FIG. 2C is that the firstsemiconductor layer 224 is etched to form a textured surface 2241.Following, a similar process as the embodiment in FIG. 2A, a thirdplanarization layer (not shown) is formed by spin coating method such asspin-on glass (SOG) or benzocyclobutene (BCB) to cover and fill thetextured spaces of the upper surface 2241 of the first conductivity typesemiconductor layer 220 and then the third planarization layer (notshown) is patterned and solidified to form a fourth planarization layer291 by etching or lithography method wherein part of the upper surface2241 of the first conductivity type semiconductor layer 224 is exposed.The position of the fourth planarization layer 291 is not specified andcan be formed in the middle or the edge of the second conductivity typesemiconductor layer 224.

Following, a second transparent conductive oxide layer 28 is formed tocover the entire fourth planarization layer 291 and part of the uppersurface first conductivity type semiconductor layer 2241. The secondtransparent conductive oxide layer 28 includes a first portion 281 and asecond portion 282 wherein the first portion 281 is formed in contactwith the entire fourth planarization layer 291 which is substantiallyflat and the second portion 282 is formed on the upper surface of thefirst conductivity type semiconductor layer 2241 having a firstplurality of cavities 2821 in contact with the upper surface of thefirst conductivity type semiconductor layer 2241 and a second pluralityof cavities 2822 formed in the upper surface of the second portion 282which is opposite to the first plurality of cavities 2821. The firstplurality of cavities 2821 are shaped into cones or pyramids and formedby an epitaxy method, an etching method, or the combination thereof. Thesecond plurality of cavities 2822 are shaped into a cone or a pyramid byan etching process and extended downwards to the first plurality ofcavities 2821 of the second transparent conductive layer 28, wherein thedirection of the extension is preferably perpendicular to the topsurface of the substrate 20.

Finally, a first electrode 25 is formed on the first portion 241 of thefirst transparent conductive oxide layer 24; and a second electrode 26is formed on the first portion 281 of the second transparent conductiveoxide layer 28. The material of the electrode structure mentioned abovecan be metal material such as Cr, Ti, Ni, Pt, Cu, Au, Al, or Ag. By thecombination of the flat and textured first transparent oxide layer andthe flat and textured second transparent oxide layer, the lowerefficiency issues are solved.

Referring to FIG. 2D, in another embodiment of this application, asecond reflective metal layer 30 can be formed on the first portion 281of the second transparent conductive oxide layer 28; a first electrode25 can be formed on the first reflective metal layer 27 and a secondelectrode 26 can be formed on the second reflective layer 30 to improvethe light-emitting efficiency.

FIG. 3 is a cross-sectional view of a light-emitting device inaccordance with a third embodiment of the present application. Thedifference between the third embodiment and the first embodiment is thatan additional Distributed Bragg Reflector (DBR) layer 38 is formedbetween the conductive substrate 30 and the first semiconductor layer324.

FIG. 4 is a cross-sectional view of a light-emitting device inaccordance with a fourth embodiment of the application. The differencebetween the fourth embodiment and the first embodiment is that a metalbonding layer 41, a reflective layer 49 and a second transparentconductive oxide layer 48 is formed between the conductive substrate 40and the first semiconductor layer 424.

FIG. 5 is a cross-sectional view of a light-emitting device inaccordance with a fifth embodiment of the present application. Thedifference between the fourth embodiment and the second embodiment isthat a metal bonding layer 51, a reflective layer 59 and a secondtransparent conductive oxide layer 58 is formed between the substrate 50and the first semiconductor layer 524 and the second electrode 56 isformed on the second transparent conductive oxide layer 58.

FIGS. 6A-6B are top views of a second semiconductor layer in accordancewith a first embodiment of the present application. FIG. 6A is a topview of a second semiconductor layer 120, the second planarization layer(not shown) can be formed on part of the second semiconductor layer 120.After forming the second planarization layer, the first transparentconductive oxide layer 14 is formed on part of the second planarizationlayer and having a first portion 141 in contact with the entire secondplanarization layer which is substantially flat and a second portionformed on the second semiconductor layer 120 with a textured surface.Following, a first electrode 15 is formed on the first portion 141 ofthe first transparent conductive oxide layer 14. In this embodiment,part of the first transparent conductive oxide layer 14 is not coveredby the first electrode 15 and is extended toward the other end of thelight emitting chip as a finger to spread the current.

Referring to FIG. 6B, in another embodiment, the first electrode 15 canhave a secondary branch 151 having a finger-like pattern extended towardthe other end of the light emitting device to have better currentspreading. The first transparent conductive oxide layer 14 can furtherhave a secondary branch 1411 having a finger-like pattern extendedtoward the other end of the light emitting device and a third classbranch 1412 extended from the secondary branch 1411 as a transparentfinger to increase the current spreading efficiency. In this embodiment,part of the secondary branch 1411 and the third branch 1412 of the firsttransparent conductive oxide layer is not covered by the secondarybranch of the first electrode 151. Since the secondary branch of thefirst transparent conductive oxide layer 1411 and the third branch 1412of the first transparent conductive oxide layer is formed on the secondplanarization layer (not shown), the structure is also substantiallyflat and can have a better current spreading efficiency.

FIGS. 7A-7B are top views of a second semiconductor layer in accordancewith a first embodiment of the present application. FIG. 7A is a topview of a second semiconductor layer 220, the second planarization layer(not shown) can be formed on part of the second semiconductor layer 220.After forming the second planarization layer, the first transparentconductive oxide layer 24 is formed on part of the second planarizationlayer and having a first portion 241 in contact with the entire secondplanarization layer which is substantially flat and a second portionformed on the second semiconductor layer 220 with a textured surface.Following, a first electrode 25 is formed on the first portion 241 ofthe first transparent conductive oxide layer 24. In this embodiment,part of the first transparent conductive oxide layer 24 is not coveredby the first electrode 25 and is extended toward the other end of thelight emitting chip as a finger to spread the current.

Referring to FIG. 7B, in another embodiment, the first electrode 25 canhave a secondary branch 251 having a finger-like pattern extended towardthe other end of the light emitting device to have better currentspreading. The first transparent conductive oxide layer 24 can furtherhave a secondary branch 2411 having a finger-like pattern extendedtoward the other end of the light emitting device and a third classbranch 2412 extended from the secondary branch 2411 as a transparentfinger to increase the current spreading efficiency. In this embodiment,part of the secondary branch 2411 and the third branch 2412 of the firsttransparent conductive oxide layer is not covered by the secondarybranch of the first electrode 251. Since the secondary branch of thefirst transparent conductive oxide layer 2411 and the third branch 2412of the first transparent conductive oxide layer is formed on the secondplanarization layer (not shown), the structure is also substantiallyflat and can have a better current spreading efficiency.

In the aforementioned embodiments, the conductive substrates 10, 30 and40 are made of SiC, GaAs, GaN, AlN, GaP, Si, or the combination thereof,and the substrates 20 and 50 are made of sapphire, glass, or thecombination thereof.

In the aforementioned embodiments, the first transparent conductiveoxide layer 14 and 24, the second transparent conductive oxide layer 28is made of indium tin oxide (ITO), cadmium tin oxide (CTO), antimony tinoxide, zinc indium oxide, aluminum zinc oxide, zinc antimony oxide, orthe combinations thereof; and is formed by an E-beam evaporation method,an ion-sputtering method, a thermal-evaporation method, or anycombination thereof. Taking ITO as an example, the thickness of thefirst transparent conductive oxide layer 14 and 24, the secondtransparent conductive oxide layer 28 is from 50 μm to 1 μm and thetransmissivity is above 50% when the range of the related wavelength isfrom 300 μm to 700 μm.

In the aforementioned embodiments, the metal bonding layer 41, 51 ismade of indium (In), tin (Sn), gold-tin (AuSn), or the combinationthereof.

The DBR layer 38 is formed by stacked semiconductor layers and thereflective layers 49, 59 are made of In, Sn, Ai, Au, Pt, Zn, Ag, Ti, Pb,Pd, Ge, Cu, AuBe, AuGe, Ni, PbSn, AuZn, or the combination thereof. Thefirst and second reflective metal layers 17, 27 and 30 are made of Al orAg.

Although the drawings and the illustrations above are corresponding tothe specific embodiments individually, the element, the practicingmethod, the designing principle, and the technical theory can bereferred, exchanged, incorporated, collocated, coordinated except theyare conflicted, incompatible, or hard to be put into practice together.

Although the present application has been explained above, it is not thelimitation of the range, the sequence in practice, the material inpractice, or the method in practice. Any modification or decoration forpresent application is not detached from the spirit and the range ofsuch.

What is claimed is:
 1. A light-emitting device comprising: alight-emitting stacked layer having first conductivity typesemiconductor layer; a light-emitting layer formed on the firstconductivity type semiconductor layer; and a second conductivity typesemiconductor layer formed on the light-emitting layer, wherein theupper surface of the second conductivity type semiconductor layer is atextured surface; a first planarization layer formed on a first part ofthe second conductivity type semiconductor layer; a first transparentconductive oxide layer formed on the first planarization layer and asecond part of the second conductivity type semiconductor layer,including a first portion in contact with the first planarization layerand a second portion having a first plurality of cavities in contactwith the second conductivity type semiconductor layer; a first electrodeformed on the first portion of the first transparent conductive oxidelayer; and a first reflective metal layer formed between the firsttransparent conductive oxide layer and the first electrode.
 2. Thelight-emitting device according to claim 1, further comprising a secondplurality of cavities formed in the upper surface of the second portionof the first transparent conductive oxide layer which is opposite to thefirst plurality of cavities.
 3. The light-emitting device according toclaim 1, further comprising a substrate formed below the light-emittingstacked layer.
 4. The light-emitting device according to claim 1,wherein the material of the first transparent conductive oxide layer isselected form the group consisting of indium tin oxide (ITO), cadmiumtin oxide (CTO), antimony tin oxide, zinc indium oxide, aluminum zincoxide, zinc antimony oxide, and the combinations thereof.
 5. Thelight-emitting device according to claim 1, wherein the firstplanarization layer is substantially flat and comprises spin-on glass(SOG) or benzocyclobutene (BCB).
 6. The light-emitting device accordingto claim 5, wherein the SOG comprises a dielectric material.
 7. Thelight-emitting device according to claim 1, wherein the material of thelight-emitting stacked layer contains one or more elements selected fromthe group consisting of Ga, Al, In, As, P, N and Si.
 8. A light-emittingdevice comprising: a light-emitting stacked layer having firstconductivity type semiconductor layer; a light-emitting layer formed onthe first conductivity type semiconductor layer; and a secondconductivity type semiconductor layer formed on the light-emittinglayer, wherein the upper surface of the second conductivity typesemiconductor layer is a textured surface; a first planarization layerformed on a first part of the second conductivity type semiconductorlayer; a first transparent conductive oxide layer formed on the firstplanarization layer and a second part of the second conductivity typesemiconductor layer, including a first portion in contact with the firstplanarization layer and a second portion having a first plurality ofcavities in contact with the second conductivity type semiconductorlayer; and a first electrode formed on the first portion of the firsttransparent conductive oxide layer, wherein the first transparentconductive oxide layer further has a secondary branch not covered by thefirst electrode and extended toward an end of the light emitting device.9. The light-emitting device according to claim 8, wherein the firsttransparent conductive oxide layer further has a third branch extendedfrom the secondary branch and not covered by the first electrode.
 10. Alight-emitting device comprising: a light-emitting stacked layer havingfirst conductivity type semiconductor layer; a light-emitting layerformed on the first conductivity type semiconductor layer; and a secondconductivity type semiconductor layer formed on the light-emittinglayer, wherein the upper surface of the second conductivity typesemiconductor layer is a textured surface; a first planarization layerformed on a first part of the second conductivity type semiconductorlayer; a first transparent conductive oxide layer formed on the firstplanarization layer and a second part of the second conductivity typesemiconductor layer, including a first portion in contact with the firstplanarization layer and a second portion having a first plurality ofcavities in contact with the second conductivity type semiconductorlayer; a first electrode formed on the first portion of the firsttransparent conductive oxide layer; and a second planarization layerformed on a first part of the upper surface of the first conductivitytype semiconductor layer and a second transparent conductive oxide layerformed on the second planarization layer and a second part of the firstconductivity type semiconductor layer, the second transparent conductiveoxide layer including a first portion in contact with the secondplanarization layer and a second portion having a third plurality ofcavities in contact with the first conductivity type semiconductorlayer.
 11. The light-emitting device according to claim 10, wherein thesecond planarization layer is substantially flat and comprises spin-onglass (SOG) or benzocyclobutene (BCB).
 12. The light-emitting deviceaccording to claim 11, further comprising a fourth plurality of cavitiesformed in the upper surface of the second portion of the secondtransparent conductive oxide layer which is opposite to the thirdplurality of cavities.
 13. The light-emitting device according to claim10, further comprising a second electrode formed on the first portion ofthe second transparent conductive oxide layer.
 14. The light-emittingdevice according to claim 13, further comprising a second reflectivelayer formed between the second electrode and the second transparentconductive oxide layer.
 15. The light-emitting device according to claim3, further comprising a bonding layer formed between the light-emittingstacked layer and the substrate.
 16. The light-emitting device accordingto claim 15, further comprising a third transparent conductive oxidelayer formed between the light-emitting stacked layer and the bondinglayer.
 17. The light-emitting device according to claim 2, wherein thefirst plurality of cavities and the second plurality of cavities areshaped into cones or pyramids.
 18. The light-emitting device accordingto claim 12, wherein the third plurality of cavities and the fourthplurality of cavities are shaped into cones or pyramids.
 19. Thelight-emitting device according to claim 1, wherein the area of thefirst reflective metal layer is substantially the same as the area ofthe first electrode.